1. Field of the Invention
The present invention relates to a sheet feeding apparatus wherein sheet-like paper is sucked and fed by a vacuum type belt from above the sheet bundle stacked on a sheet tray, and sent to a sheet feeding apparatus and image forming apparatus of a photocopier, printer, facsimile, printing machine and others which are provided with this sheet feeding apparatus.
2. Description of Related Art
One of the sheet feeding apparatuses known in the conventional art is the one having a sheet tray capable of stacking sheet-like paper wherein paper is sucked on a vacuum type belt using negative pressure and is fed in a predetermined direction. An image forming apparatus having such a sheet feeding apparatus is also known.
For example, the Japanese Unexamined Patent Application Publication No. 9-86699 proposes a sheet feeding apparatus including: a sheet stacking device; a side regulating device for regulating the position perpendicular to the direction of feeding the sheet on the sheet stacking device; a feed device for feeding the vacuum-sucking and feeding the lowermost one of the stacked sheets; and a separation device wherein air is jetted onto the side of the sheets on the sheet stacking device to separate the sheet having been vacuum-sucked by the feed device from other sheets.
The feed apparatus disclosed in the Japanese Unexamined Patent Application Publication No. 9-86699 is considered to provide an excellent technique wherein the lowermost of the sheets is sucked by the feed device and separated from other sheets independently of the type of sheet, and the lowermost sheet having been separated is fed correctly by the feed device.
As one form of the specification, a sheet feeding apparatus can be designed in such a way that the vacuum type belt is arranged to ensure that paper is sucked from above the sheet bundle and is fed. This arrangement, however, is not intended in the Japanese Unexamined Patent Application Publication No. 9-86699.
As described above, the applicants of the present invention have manufactured a sheet feeding apparatus wherein a vacuum type belt is arranged above the stacked sheets of paper and the uppermost sheet of paper is sucked by this vacuum type belt and is separated, and have conducted sheet feed tests using a large quantity of paper.
However, the aforementioned applicants have encountered the problem wherein the smooth feed of sheets of paper cannot be achieved sometimes.
To put it more specifically, there is a problem wherein the side edge of paper is displaced beyond the side regulating member through a slight clearance between the lowermost surface of the vacuum type belt opposed to the uppermost paper, and the top end of the side regulating member for regulating the side of the paper, is provided perpendicular to the direction wherein paper is fed.
In the meantime, a sheet tray capable of stacking and storing sheets of paper is provided as a constituent component of the sheet feeding apparatus. It is preferred from the view of conveyance to arrange this sheet tray in such a way that the sheet tray can be inserted or removed in the lateral direction (i.e., can be pulled out in the direction of the front door) by opening the door on the front of the image forming apparatus or the housing incorporating the sheet tray.
However, to prevent the displacement (misalignment) of the sheet mentioned above, it is necessary to ensure that the top end of the side regulating member is higher than the lowermost surface of the vacuum type belt. If this requirement is met, however, difficulties will be encountered in the insertion and removal of the sheet tray.
To find out the documents wherein such problems were disclosed, terms were set as appropriate according to the International Patent Classifications G03G, B65H and B41J, and a search was carried out to check the Abstract and Claim. However, no such documents have been found.